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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: Field.html 842 2015-03-07 18:20:42Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.core;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import com.google.common.reflect.TypeToken;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import org.jsimpledb.util.ByteWriter;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.jsimpledb.util.UnsignedIntEncoder;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>/**<a name="line.15"></a>
<span class="sourceLineNo">016</span> * Represents a field in an {@link ObjType} or a ({@linkplain SimpleField simple}) sub-field of a {@link ComplexField}.<a name="line.16"></a>
<span class="sourceLineNo">017</span> *<a name="line.17"></a>
<span class="sourceLineNo">018</span> * @param &lt;T&gt; Java type for the field's values<a name="line.18"></a>
<span class="sourceLineNo">019</span> */<a name="line.19"></a>
<span class="sourceLineNo">020</span>public abstract class Field&lt;T&gt; extends SchemaItem {<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>    final TypeToken&lt;T&gt; typeToken;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>    /**<a name="line.24"></a>
<span class="sourceLineNo">025</span>     * Constructor for normal fields of an {@link ObjType}.<a name="line.25"></a>
<span class="sourceLineNo">026</span>     *<a name="line.26"></a>
<span class="sourceLineNo">027</span>     * @param name the name of the field<a name="line.27"></a>
<span class="sourceLineNo">028</span>     * @param storageId field storage ID<a name="line.28"></a>
<span class="sourceLineNo">029</span>     * @param schema schema version<a name="line.29"></a>
<span class="sourceLineNo">030</span>     * @param typeToken Java type for the field's values<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * @throws IllegalArgumentException if any parameter is null<a name="line.31"></a>
<span class="sourceLineNo">032</span>     * @throws IllegalArgumentException if {@code name} is invalid<a name="line.32"></a>
<span class="sourceLineNo">033</span>     * @throws IllegalArgumentException if {@code storageId} is non-positive<a name="line.33"></a>
<span class="sourceLineNo">034</span>     */<a name="line.34"></a>
<span class="sourceLineNo">035</span>    Field(String name, int storageId, Schema schema, TypeToken&lt;T&gt; typeToken) {<a name="line.35"></a>
<span class="sourceLineNo">036</span>        super(name, storageId, schema);<a name="line.36"></a>
<span class="sourceLineNo">037</span>        if (typeToken == null)<a name="line.37"></a>
<span class="sourceLineNo">038</span>            throw new IllegalArgumentException("null typeToken");<a name="line.38"></a>
<span class="sourceLineNo">039</span>        this.typeToken = typeToken;<a name="line.39"></a>
<span class="sourceLineNo">040</span>    }<a name="line.40"></a>
<span class="sourceLineNo">041</span><a name="line.41"></a>
<span class="sourceLineNo">042</span>// Public methods<a name="line.42"></a>
<span class="sourceLineNo">043</span><a name="line.43"></a>
<span class="sourceLineNo">044</span>    /**<a name="line.44"></a>
<span class="sourceLineNo">045</span>     * Get the Java type corresponding to this field.<a name="line.45"></a>
<span class="sourceLineNo">046</span>     *<a name="line.46"></a>
<span class="sourceLineNo">047</span>     * @return this field's type<a name="line.47"></a>
<span class="sourceLineNo">048</span>     */<a name="line.48"></a>
<span class="sourceLineNo">049</span>    public TypeToken&lt;T&gt; getTypeToken() {<a name="line.49"></a>
<span class="sourceLineNo">050</span>        return this.typeToken;<a name="line.50"></a>
<span class="sourceLineNo">051</span>    }<a name="line.51"></a>
<span class="sourceLineNo">052</span><a name="line.52"></a>
<span class="sourceLineNo">053</span>    /**<a name="line.53"></a>
<span class="sourceLineNo">054</span>     * Get the value of this field in the given object.<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * Does not alter the schema version of the object.<a name="line.55"></a>
<span class="sourceLineNo">056</span>     *<a name="line.56"></a>
<span class="sourceLineNo">057</span>     * @param tx transaction<a name="line.57"></a>
<span class="sourceLineNo">058</span>     * @param id object id<a name="line.58"></a>
<span class="sourceLineNo">059</span>     * @return this field's value in the specified object<a name="line.59"></a>
<span class="sourceLineNo">060</span>     * @throws DeletedObjectException if no object with ID equal to {@code id} is found<a name="line.60"></a>
<span class="sourceLineNo">061</span>     * @throws UnknownTypeException if {@code id} specifies an unknown object type<a name="line.61"></a>
<span class="sourceLineNo">062</span>     * @throws UnknownFieldException if this field does not exist in the specified object<a name="line.62"></a>
<span class="sourceLineNo">063</span>     * @throws StaleTransactionException if this transaction is no longer usable<a name="line.63"></a>
<span class="sourceLineNo">064</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.64"></a>
<span class="sourceLineNo">065</span>     */<a name="line.65"></a>
<span class="sourceLineNo">066</span>    public abstract T getValue(Transaction tx, ObjId id);<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>    /**<a name="line.68"></a>
<span class="sourceLineNo">069</span>     * Determine if this field in the specified object has its default value in the specified {@link Transaction}.<a name="line.69"></a>
<span class="sourceLineNo">070</span>     *<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * @param tx {@link Transaction} containing field state<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * @param id object ID<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * @return true if this field is set to its initial default value in object {@code id}, otherwise false<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * @throws DeletedObjectException if no object with ID equal to {@code id} is found<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * @throws UnknownTypeException if {@code id} specifies an unknown object type<a name="line.75"></a>
<span class="sourceLineNo">076</span>     * @throws StaleTransactionException if this transaction is no longer usable<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.77"></a>
<span class="sourceLineNo">078</span>     */<a name="line.78"></a>
<span class="sourceLineNo">079</span>    public abstract boolean hasDefaultValue(Transaction tx, ObjId id);<a name="line.79"></a>
<span class="sourceLineNo">080</span><a name="line.80"></a>
<span class="sourceLineNo">081</span>    /**<a name="line.81"></a>
<span class="sourceLineNo">082</span>     * Apply visitor pattern.<a name="line.82"></a>
<span class="sourceLineNo">083</span>     *<a name="line.83"></a>
<span class="sourceLineNo">084</span>     * @param target target to invoke<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * @param &lt;R&gt; visitor return type<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * @return value from the method of {@code target} corresponding to this instance's type<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * @throws NullPointerException if {@code target} is null<a name="line.87"></a>
<span class="sourceLineNo">088</span>     */<a name="line.88"></a>
<span class="sourceLineNo">089</span>    public abstract &lt;R&gt; R visit(FieldSwitch&lt;R&gt; target);<a name="line.89"></a>
<span class="sourceLineNo">090</span><a name="line.90"></a>
<span class="sourceLineNo">091</span>// Non-public methods<a name="line.91"></a>
<span class="sourceLineNo">092</span><a name="line.92"></a>
<span class="sourceLineNo">093</span>    @Override<a name="line.93"></a>
<span class="sourceLineNo">094</span>    abstract FieldStorageInfo toStorageInfo();<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span>    /**<a name="line.96"></a>
<span class="sourceLineNo">097</span>     * Copy field value between transactions.<a name="line.97"></a>
<span class="sourceLineNo">098</span>     *<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * &lt;p&gt;<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * This method assumes both objects exist and both transactions are locked.<a name="line.100"></a>
<span class="sourceLineNo">101</span>     * &lt;/p&gt;<a name="line.101"></a>
<span class="sourceLineNo">102</span>     */<a name="line.102"></a>
<span class="sourceLineNo">103</span>    abstract void copy(ObjId srcId, ObjId dstId, Transaction srcTx, Transaction dstTx);<a name="line.103"></a>
<span class="sourceLineNo">104</span><a name="line.104"></a>
<span class="sourceLineNo">105</span>    /**<a name="line.105"></a>
<span class="sourceLineNo">106</span>     * Build the key (or key prefix) for this field in the given object.<a name="line.106"></a>
<span class="sourceLineNo">107</span>     */<a name="line.107"></a>
<span class="sourceLineNo">108</span>    byte[] buildKey(ObjId id) {<a name="line.108"></a>
<span class="sourceLineNo">109</span>        return Field.buildKey(id, this.storageId);<a name="line.109"></a>
<span class="sourceLineNo">110</span>    }<a name="line.110"></a>
<span class="sourceLineNo">111</span><a name="line.111"></a>
<span class="sourceLineNo">112</span>    /**<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * Build the key (or key prefix) for this field in the given object.<a name="line.113"></a>
<span class="sourceLineNo">114</span>     */<a name="line.114"></a>
<span class="sourceLineNo">115</span>    static byte[] buildKey(ObjId id, int storageId) {<a name="line.115"></a>
<span class="sourceLineNo">116</span>        final ByteWriter writer = new ByteWriter();<a name="line.116"></a>
<span class="sourceLineNo">117</span>        id.writeTo(writer);<a name="line.117"></a>
<span class="sourceLineNo">118</span>        UnsignedIntEncoder.write(writer, storageId);<a name="line.118"></a>
<span class="sourceLineNo">119</span>        return writer.getBytes();<a name="line.119"></a>
<span class="sourceLineNo">120</span>    }<a name="line.120"></a>
<span class="sourceLineNo">121</span>}<a name="line.121"></a>
<span class="sourceLineNo">122</span><a name="line.122"></a>




























































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